I've been meaning to ask about that long time ago: can you recommend any techniques or workflows fitting for a model that does not have any high-poly source mesh available?
In particular, I'm very interested to know about the following:
- First question: ambient occlusion baking. Are there any caveats or problems involved if you're using the same lowpoly mesh both as a source and as a target in xNormal/Mudbox bake setups? Obviously, these tools were originally intended for capturing detail from highpoly meshes, maybe there are some issues that could arise when I use identical lowpoly meshes. If there are indeed potential issues, how should I avoid them? Are there any specific tricks that can be used to make AO bakes from lowpoly better in quality?
- Hard/soft edges. I am very frequently using hard and soft edges to define how my geometry should be lit (faceted designs etc). But, as I see from some brilliantly detailed threads here (especially this one from EarthQuake), best way to go about using hard edges is to leave them ONLY at UV seams (if they are even necessary there, of course - otherwise use none at all). They help avoid artifacts in baked normal maps too. Unfortunately, it's does not sound like my models at all.
And that's alright, and I'm willing to remake my lowpoly geometry to use as few hard edges as possible. Only one problem: as I have mentioned, most of the models I have to deal with have no source highpoly geometry, therefore I can't just bake a normal map from it, leave everything smooth, and get a nice looking e.g. hardsurface prop with defined hard edges.
So, second question is: Is there a simple way to bake a normal map from lowpoly mesh that will represent the shading I currently have (lots of hard edges, soft edges used only to give smooth look to "curved" parts)? I could then optimize my lowpoly to use as few hard edges as possible, and apply such a normal map onto it to get the desired look back. I have already tried baking normals from lowpoly to lowpoly, but I don't think that's how things work - as you can guess, the result is completely empty normal map. The process of getting the desired map I have described probably involves more steps. Any ideas?
- Third question: what is the best way to go about creating normal maps for lowpoly meshes without highpoly source available? Of course, baking is out of the question. Is there any other way than using nDo? What I'm currently doing is painting grayscale height map over my texture in Photoshop, and then feed it to any normal map converter, be it NVIDIA plugin, CrazyBump or Unity importer). I guess nDo is the only other option for models like these?
And out of the subject of manually painted details: I would like to know if there is a simple way to make blank normal map with tiny, properly oriented areas of normals representing bevels placed on every hard edge. You know, something that would make hard edges more natural, and less sharp.
To elaborate a bit: I'm not talking about extremely tiny models for mobile devices or other similar applications, but rather about meshes around 500-2000 polygons in size with typical texture size of x512 or x1024 and advanced materials available (emissive, specular, normals). Think RTS games. Or, I don't know, Kerbal Space Program. Not a very limited environment.
I should post some examples, sorry. I'm looking to spice up models like these:
Thanks in advance for any answers!